As the infrastructure of major cities and towns in the developed world age, the sewer systems weaken. Pipe degradation, system blockage, water infiltration, and sewer leakage are major problems that aging sewer systems experience. As these problems persist, the sewer system may eventually experience total failure and entire sections of the sewer system may collapse. As a result, sinkholes may form and sewers may back up into homes and places of business. One method of addressing this critical infrastructure problem is the use of pipe lining techniques to rehabilitate existing sewer systems.
Cured-in-place pipelining is one such technique that includes rehabilitating an existing sewer system by creating a new wall within an existing pipe or manhole. A liner, impregnated with a resinous material capable of curing and hardening, is inverted or pulled into a damaged structure (typically a pipe or manhole). The liner is pressed against the wall of the existing structure, and the resinous material is allowed to cure and harden. The result is a replacement structure wall having the older wall or “host pipe” on the exterior. The cured-in-place liner acts to alleviate the problems caused by structural defects and blockages in the existing sewer system. Even in sewer systems where the main pipes or manholes have been rehabilitated with a cured-in-place pipe or other pipe liners, problems still arise. Some of those problems are caused by shrinkage of the liner and unsealed areas at the pipe ends, the pipe junctions, or the manholes and other adjoining structures.
Shrinkage of a liner after installation presents a problem for the longevity and effectiveness of a sewer system or other pipeline. Most resinous materials experience some shrinkage after installation within an existing pipe or manhole. Once the liner material has been installed, an annulus between the host pipe and the liner is created due to this shrinkage of the resinous material or due to surface irregularities of the structure's wall. The amount of shrinkage by a liner depends on the materials used, the thickness of the liner, the depth of the structure, the ambient temperatures, as well as several other factors. This shrinkage allows water and debris to enter into the sewer system from the ground surrounding the pipes, allows effluent to escape into the ground surrounding the pipes, and allows roots from surrounding vegetation to enter the annulus between the host structure and the liner.
In sewer systems where the main pipes have been rehabilitated with a cured-in-place pipe, unsealed connections at service and manhole junctions create problems. An unsealed connection is generally a product of installing a pipe liner within the main pipe, then using a cutting tool on the pipe liner at the connection to reinstate service. Current methods are described for example in U.S. Pat. Nos. 5,587,126; 6,641,688; and 7,131,791, which are all incorporated by reference in their entirety. Once service is reinstated to the service pipes by the use of the cutting tool, the service pipes may still include leaks, cracks or other structural defects that allow infiltration or exfiltration of fluids or sediment at or around the junction of the main and service pipe. The service pipe and junction with the main pipe may be further sealed or rehabilitated by installing a hydrophilic or hydrophobic sealing member. U.S. Pat. No. 7,975,726, which is incorporated by reference in its entirety, discloses applying a paste in the form of a ring or band to the liner to help prevent infiltration or exfiltration of fluids or sediment. One problem with using these types of materials is that the paste is compressed against the pipe by the expanding liner or bladder before it cures, which disperses and thins the paste and reduces the effectiveness of the sealing member.
Similarly, once the main pipe and the junctions of the main and service pipes have been rehabilitated and sealed, the manhole and the junction of the main pipe and the manhole remain at risk for allowing unwanted infiltration or exfiltration of fluids and sediment. Conventional manholes include a lower or bottom pan, a barrel with a diameter no greater than the adjacent pan, a concentric or eccentric cone extending upwardly from the barrel, one or more adjusting rings to adjust the overall height of the manhole, and a casting frame on top of the adjusting rings to support a lid at an elevation substantially level with the surrounding pavement. Manholes may be used for many purposes, including acting as catch basins for storm water drainage, providing access to buried pipelines, junction chambers at the intersection of sewer lines, and constructing reservoirs or wetwells for pump stations. As such, the manhole structure is a critical point to seal within the sewer system because it is an area that is inundated with fluids and sediment. The issue of sealing a manhole utilizing cured-in-place pipelining techniques has been previously addressed in U.S. Pat. No. 7,670,086, which is hereby incorporated by reference in its entirety. However, unless the junction between the manhole and sewer pipe is properly sealed, ground water will continue to run along the main pipe until it can enter the sewer system where the main pipe joins the manhole. Additionally, in a conventional manhole, the areas between the bottom pan, the barrel, the cone, and the adjusting rings are prone to experiencing water infiltration and exfiltration even when a manhole liner has been installed. Some prior methods disclose placing a hydrophobic or hydrophilic sealing member at the junction between the pipe and the manhole and/or within the manhole to help prevent water infiltration. U.S. Pat. No. 8,640,737, which is incorporated by reference in its entirety, discloses applying a liquid or semi-liquid sealing member into the manhole adjacent to an area of the manhole prone to water infiltration. The liquid or semi-liquid sealing member may be a hydrophilic or hydrophobic grout or paste. One problem with using these types of materials is that the liquid or semi-liquid sealing member is compressed against the pipe by the expanding liner or bladder before it cures, which disperses and thins the paste and reduces the effectiveness of the sealing member.
Therefore, a need in the art exists for an apparatus and method for more effectively sealing underground structures such as pipes and manholes and junctions between underground structures using a liquid or semi-semi-liquid such as a hydrophilic or hydrophobic grout or paste.